This invention relates generally to condition responsive circuits and, more particularly, to a condition responsive circuit which may be utilized in environments such as hospitals and the like for signalling the departure of a patient from a hospital bed.
One of the common hospital accidents occurs when a patient climbs off a hospital bed and injures himself such as by falling or stumbling. This will frequently occur when a patient who is too weak to walk unaided deliberately attempts to climb off the bed. It may also occur when the patient is not totally aware of his physical acts for one reason or another.
The departure of a patient from a hospital bed results in the removal of pressure (weight) from the bed. Therefore, the present invention is responsive to a change in conditions, namely, changes in pressure.
While various systems have been developed for detecting the pesence or absence of pressure, it must be appreciated that in a hospital environment it is undesirable to have a hospital bed connected to a source of electric power. Not only is there a psychological problem when the bed itself is connected to a source of power, but there is always a danger of shock if liquids are spilled on the bed.
Therefore, it any current is to be supplied to the bed it must be nominal. However, if a self-contained battery system is utilized, the useful life of this system is quite short if the battery is always in an on condition.
It is therefore a principal object of the present invention to provide a condition responsive circuit which normally draws only a nominal current.
It is a further object of the present invention to provide a hospital bed alarm system which signals the departure of a patient from a bed.
It is yet another object of the present invention to provide a self-contained signal circuit responsive to a change in a physical condition, such as the presence or absence of pressure.